Although autoimmunity is as an over response of the immune system and immunodeficiency is an under response, immunodeficiency diseases and autoimmune diseases are not mutually exclusive since both represent profound dysregulation of the immune response. Immunodeficiencies are associated with impaired function of one of the cells or soluble mediators the immune system. For example, approximately 20 % of patients with common variable immunodeficiency (CVID), a B cell defect, develop an autoimmune condition such as idiopathic thrombocytopenia (ITP), hemolytic anemia, rheumatoid arthritis, sicca syndrome, primary biliary cirrhosis, and pernicious anemia. Systemic lupus erythematosis (SLE) may also co-occur with CVID, but the development of SLE may precede or follow the development of CIVD, illustrating the two way relationship between autoimmunity and immunodeficiency based on fundamental defects in immunoregulation deficiency. New opportunities to study genetic mechanisms that help to explain the connection between T cell deficiencies in autoimmune disease are rapidly emerging. In addition to the human disorders some of these genetic defects have been reproduced in experimental animals where they are providing the unique opportunity to study the molecular mechanisms underlying in both autoimmunity and immunodeficiency. We believe that these exciting opportunities to explore the relationship between immunodeficiency diseases and autoimmune diseases makes a meeting on this topic particularly timely. The goal of the colloquium is to identify critical research areas that represent unmet needs or are presently under explored. The meeting will bring together expert investigators in different specialties to identify the basic issues that may explain the co-occurrence of immunodeficiency and autoimmunity. At the same time new opportunities for translational research will arise to benefit immunodeficiency patients who may develop autoimmune disease or autoimmune disease patients at risk for immunodeficiency. By bringing together geneticists, hematologists, infectious disease specialists, and immunologists together with molecular scientists we intend to challenge and expand the way we presently think about the regulation of immune responses.